Reactor



Feb. 13, 1945. 1. A. MEKLER ET AL REACTOR Filed April 25 1941 FIG. 3

FIG.

INVENTORS LEV A. MEKLER CLARENCE G. GERHOLD ATTORNEY FIG. 4

Patented Feb. is, 1945 r 2,369,478

UNITED STATES PATENT orrlca Lev A. Mekler and Clarence G. Gerhold,Chicago, Ill., assignors to Universal Oil Products Company, Chicago,Ill., corporation of Delaware Application April 25, 1941, Serial No.390,224 11 Claims. (Cl. 23-288) This invention relates to an improvedform of The reactor which we provide employs a pluralreactor in which toconduct conversion reactions ity of individual beds of catalyst orcontact main the presence of solid granular catalytic or nonterialdisposed in superimposed relationship on catalytic contact material. Itwill be found partrays within the shell of the reactor and theinticularly advantageous as applied to catalytically coming stream ofreactants or reactivating gases, promoted hydrocarbon conversionreactions, such as the case may be, is divided into a plurality of ascracking, dehydrogenation, isomerization and separate streams each ofwhich is passed through the like, but is broadly applicable to manyother an individual bed. The separate streams of retypes of reactionsand particularly those in which sulting reaction products are thereaftercomrelatively low operating pressures and low presmingled and thecommingled stream discharged sure drop through the catalyst or contactmatefrom the reactor. The trays are so constructed rial is advantageous.and arranged that a space is provided above each The features of thereactor provided permit its catalyst bed which spaces directlycommunicate use for conducting .both endothermic and exowith an annularspace provided between the trays thermic reactions under substantiallyadiabatic 15 and the shell of the reactor. A separate space isconditions. The reactor will be found particuprovided beneath eachcatalystbed and the first larly advantageous for the catalytic crackingof and second named spaces communicate with each hydrocarbon oils, forexample, and similar reother only through the catalyst beds. The spaceactions wherein the catalyst or contact material beneath each catalystbedfdir ly o u i t requires frequent periodic reactivation or regenwitha continuous central conduit formedby seeration. For example,incatalytic cracking delerially connected conduit sections individual toterious heavy conversion products of a carbonathe several trays. Inletmeans for reactants and ceous or hydrocarbonaceous nature, resultingreactivating gases directly communicate with the from cracking of thehydrocarbons (which re-' annular space between the trays and the shellaction is endothermic) are deposited on the cataand outlet meansprovided in the shell directly lyst and must be periodically removedtherefrom communicate with the central conduit. to restore its activity.Such regeneration of the As a special feature of the invention, thetrays a y i p ed y urning the deposited of the reactor are individuallysupported from combustible materials from the catalyst mass in r thewall of the vessel, thus eliminating any aca stream of hot oxygen-conainin gases and this, cumulated load On the lower trays of the assemofcourse, is an exothermic reaction. Reactors bly and permitting lighterconstruction of the 0f the type herein prov y e e p oyed for trays thanwould otherwise be required. The this service by providing a pluralitythereof, each trays are supported by means of suitable lugs or ofwhichis alternately utilized as a zone in which the like disposed atspaced points around their to conduct the cracking reaction and as aouter Walls and engaged with other lugs or simizone in which toaccomplish regeneration of lar supporting means disposed at spacedpoints .the catalyst. Both reactions may be conducted about the interiorof the shell and secured thereunder substantially adiabatic conditionsin the to. In plac ng the trays within the shell they sense that nocirculating convective medium is may be oriented so that the s requiredto supply heat to the endothermic reacthe shell and on the trays a vtion and to abstract heat from the exothermic alignment, thus permittingthe lower trays to reaction, as has heretofore been considered necpassby the upper lugs on the shell essary in catalytic cracking. By use ofthe type lowered into the shell to the requiredyelevation of reactorherein provided, the total heat required and turned to bring the lugsinto vertical alignfor conducting the cracking reaction may be supmentso that the trays may rest thereon. plied to the hydrocarbon reactantsprior to their sitioning the supporting means for the trays inintroduction into the reactor, with the exception the manner provided,they are disposed in the of any heat stored in the metal parts of therecoolest portion of the reactor during that portion actor and in thecatalyst bed during the precedof the operating cycle (the reactivatinging reactivating step of the process. Except for which the reactor isoperated at relatively high incidental radiation losses from thereactor, the temperatures, since they are disposed in the dionly heatabstracted during exothermic regenrect path of the stream of incomineration of the catalyst is that carried away in the gases, which is muchcooler tha outgoing stream of spent or partially spent restream of thespent or partially activating gases. ing gases.

As another feature of the invention, the construction provided obviatesstresses due to any difference in expansion and contraction between thetrays and the reactor shell, the individual trays floating from theirsupports without rigid connection between the trays. In order toaccomplish this, the beds of catalyst or contact material on the traysare employed as seals, the downpipe or central conduit from each trayextending well into the catalyst bed of the succeeding lower tray. Thisfeature also eliminates the necessity of accurate machining of anyportion of the trays or accurate alignment of the superimposed trays, asis necessary when closely fitted parts are depended upon for sealing thespaces above and beneath the catalyst beds.

In the preferred embodiment of the invention, the bottoms of the traysare of substantially conical shape. This feature has several distinctadvantages. 'It provides an inlet space of gradually decreasing heightabove each catalyst bed in the direction of travel of the incomingreactants an, outlet space of gradually increasing height beneath eachcatalyst bed in the direction of travel of,the outgoing reactionproducts.

' This form of inlet space above each catalyst bed is particularlyimportant since the velocity of the gases entering the same is thusreduced, for a space f given total size, and materially decreases t edanger of blowing the catalyst particles toward the center of the bed.Since this space is not active (i. e., not occupied by catalyst) itshould be kept small for good volumetric efliciency. The decreasin inletspaces and increasingoutlet spaces above and beneath the catalyst bedsalso make for more uniform distribution of the reactants across thecatalyst bed, which is obviously important.

Another important feature of the invention resides in the insulatedouter walls of the trays which decreases heat losses to and from thecatalyst beds and insures more uniform temperatures throughout thelength of the reactor. Due to the insulated walls the incoming reactantspassing through the annular space around the trays are not materiallycooled by dissipation of heat to the catalyst beds in which theendothermic reaction is taking place and incoming reactivating gasespassing through said annular space are not substantially heated byexothermic heat of reaction generated in the catalyst beds. With thisprovision, average temperatures within the catalyst beds duringprocessing of the reactants and reactivation of the catalyst are keptcloser to the minimum and maximum temperatures at any point in thecatalyst beds and much better control of the reaction is thereforeaccomplished.

Another feature of the invention, in its preferred embodiment,reenforcing ribs are provided between the substantially conical bottomof each tray. and'the perforated plate disposed thereabove upon whichthe catalystbed rests, these ribs extending radially from the outerwalls of the tray to the central conduit. Thus a truss-like constructionis accomplished which strengthens the conical bottom and the perforateplate, permitting lighter construction than could otherwise be mployed.

, The above mentioned and other features and advantages of the improvedform of reactor herein provided will be apparent with reference to theaccompanying diagrammatic drawing and the following description thereof.

Figure l of the drawing illustrates one specific form of reactorembodying the features of the one of the trays with a portion of thescreen 26 and perforate plate l9 cut away to reveal the radialstiffening ribs 22.

Figure 4 illustrates a combustible catalyst retaining and positioningmember which may be employed in place of member 21 in Figure 2.

Referring to the drawing, the specific form of reactor here illustratedcomprises a cylindrical outer shell I having a removable upper head 2flanged at 3 to the cylindrical shell and detachably secured thereto bysuitable bolts, not illustrated. A gasket '4 or other suitable sealingmeans is provided at the joint between the flanges. A flanged inletnozzle 5 is provided on the removable upper head. The lower head 6 ofthe vessel is integral with the shell, in the case here illustrated, andis provided with a flanged outlet nozzle 1. A drain port 8 is alsoprovided in the lower head 6 with means at the port for securing aconduit thereto.

A plurality of catalyst trays I2, some of which are shown in elevationand some in cross-section in Figure 1, and one of which is illustratedin enlarged cross-sectional detail in Figure 2, are provided within theshell and are arranged in interconnected superimposed relation. Each ofthe trays comprises concentric cylindrical outer walls I3 with a spaceprovided therebetween which is closed at the top and bottom and in whichsuitable heat insulating material, such as,

for example, mineral wool, slag wool, glass wool,

exfoliated vermiculite or the like is disposed.

Suitable supporting lugs l5 are provided at spaced points about theperiphery of the outer wall of each tray and corresponding supportingduring assembly and disassembly of the trays within the shell. A traybeing lowered into the shell is -oriented So that the lugs l5 and I6 donot engage until it reaches the desired elevation and is then turned sothat lugs l5 rest upon lugs It.

The bottom closure member I! of each of the trays is substantiallyconical and slopes downward fromthe outer well I3, to which it isjoined, to a central conduit l8. Member I! is also joined to conduit i8which extends above and beneath member H, as illustrated. A perforatemember, such as plate I9 is disposed within the tray a short distanceabove member l1, leaving a space 20 therebetween of increasing heightfrom its outer to its inner extremities. Openings 2! are providedthrough the wall of member l8 at an the tray or at least to the top officiently small mesh to elevation corresponding to that of space 28 sothat space 20 in each tray is in direct communication through openings2| with the area enclosed by the central conduit I8. Perforate plate I9is also joined to the outer wall I3 and the wall of conduit I8 andradial stiffening ribs 22 are provided in space 20, these ribsbeingvertically disposed and joined along their top and bottom edges toplate I9 and member I], respectively, and along their inner and outervertical edges to conduit I8 and to the outer wall I3, respectively,giving a truss-like construction in the lower portion of the tray andstiifening the same to prevent sagging at its central portion.

'Mem-ber 23, attached to and extending upwardly from the top of the wallstructure l3, are provided at spaced points about the circumference ofthe tray and have openings therethrough whereby these members may begrasped with hooks or the like on cables to lower the trays into andlift them from the reactor shell.

When assembled within the vessel, the central conduit I8 of each of thetrays, with the exception of the lowermost tray in the assembly, extendsdownwardly into the succeeding lower tray and is provided with a portion24 of reduced diameter at its lower end which slips within the upper endof conduit I8 on the succeeding lower tray, thu forming a continuouscentral conduit through the tray assembly which is in directcommunication at spaced points along its length with each of the spaces28. Thus, an annular space is provided between the outer wall structureand the central conduit [8 in each tray above the perforate member I8,and a bed of granular contact material or catalyst, indicated at 25 inFigure 1, is provided within this annular space on each tray. Whendesired, a suitable wire mesh screen or the like, indicated at 26 inFigure 2, may be provided in each tray to rest upon the perforate memberI9 and assist in retaining the granular contact material or catalyst inplace,.particularly when the particles of the I latter are of relativelysmall size.

In assembling the trays within the reactor, each tray is lowered intoposition on its supporting lugs and the catalyst or contact material isplaced within the tray before the next succeeding higher tray of theassembly is lowered into position. The catalyst or contact material maybe placed in the trays before or after they are lowered into the helland, in either case to retain it within the annular space provided forits reception, a cylindrical member 21 is slipped over the upper end ofconduit I8, which protrudes above perforate plate I9, member 21extending upwardly from member I8 to the top of the space within thetray occupied by the catalyst bed. 'Member 21 may be constructed of wirescreenof sufretain the catalyst particles and of sufficient resiliencethat the weight of the catalyst bed will cause it to bear against memberl8 of the succeeding higher tray when the latter is inserted into thecontrol opening contact material is replaced. When this member 40 isburned away, the catalyst will settle into place along member I8 of thesucceeding higher tray which has been slipped through member 21 duringassembly. The catalyst bed will thereby serve as a seal to preventcommunication between the interior of conduit I8 and the spaces occupiedby the incoming reactants and reactivating gases, except through thecatalyst beds, so that the joints between, the conduit sections I8 neednot be closely fitted nor packed.

A baflle 28, shown in cross-section in Figure l, is provided above theuppermost catalyst tray of the assembly and comprises, in the case hereillustrated, a substantially cone-shaped top member 29 which slopesdownwardly from its central portionto its outer edges and asubstantially cone-shaped member 38 which slopes downwardly from itsouter edges to its central portion. Memthrough member 21 in assemblingthe trays. It

bers 29 and 30 are joined along their outer edges, which terminate shortof the inner surface of the reactor shell, so that the space within thereactor above baffle 28 is in direct communication with the annularspace 3| provided between the outer wall of the trays and the innersurface of the reactor shell. A cylindrical member I8, similar toconduit sections I8, is joined at its upper extremity to member 29 ofthe baffle and at a lower point to member 30. It extends into theuppermost tray of the reactor assembly and its lower end slips withinthe upper end of member I8 of the uppermost tray in the same manner asthesucceeding members I8 are nested one within the other.

BaIile 28 is held a sufiicient distance above the top of the uppermosttray that a space 32 of decreasing height from its outer to its inner,

extremity, is provided between the top of the tray and member 38 of thebaflle. Similar spaces 32 are provided between the top of each of theother trays of the assembly and the adjacent member I! of the succeedinghigher tray and each of the spaces 32 is'in direct communication withthe annular space 3| provided between the outer wall structure of thetrays and the inner surface of shell I. p

The central conduit I8", which replaces conduit I8 on the lowermost trayof the assembly may, when desired, be shorter than members I8, but isotherwise substantially the same. .Its lower end fits within a sleeve 33which is joined at its lower end'to the flanged nozzle 1 and extendsupwardly therefrom for a short distance through the outer wall structureinto the space occupied by the catalyst bed, and ports are provided at aplurality of selected points along the length of shell I in alignmentwith the thermocouple wells. Means, such as illustrated for example at31, are provided at the ports for the reception of a flange throughwhich a thermocouple sheath 38 is inserted and to which it is attached.

The following example of a catalytic cracking operation is given toillustrate the utility of the reactor above described and to show theflow of reactants, reactivating gases and reaction productstherethrough.

Hydrocarbon oil heated to a temperature at which substantial cracking.thereof will occur upon contact with the catalyst disposed within thetrays is supplied to the reactor in essentially vapor state throughnozzle 5 and the stream of hydrocarbon vapors is directed by baiile 28into the annular space 3| about the trays. The vapors flood this spaceand the spaces 32 above the catalyst bedsand pass downwardly through thelatter as a plurality of separate streams which pass individuallythrough the individual catalyst beds. The cracking reaction occurs uponcontact of the heated hydrocarbon vapors with the catalytic material andthe resulting conversion products pass from the catalyst beds throughperforate members I9 into the spaces 20 of the trays from which theyflow into the central conduit where the individual streams are joinedand from which the resulting commingled stream passes through sleeve 33and outlet nozzle 1 to succeeding separating and recovery equipment,which is not a vpart of the present invention and is therefore notillustrated.

After a period of continued operation, in the manner above described,the catalyst beds will become fouled with deposits of carbonaceous orheavy hydrocarbonaceous materials formed by the cracking reaction, andreactivation of the catalyst will be required to restore its activity.To accomplish this, after the stream of heated hydrocarbon vapors hasbeen diverted from the reactor to another similar reactor wherein thecracking reaction is continued and after the reactor wherein thecatalyst is about to be reactivated has been substantially purged offluid hydrocarbons, a stream of hot reactivating gases,

such as, for example, combustion gases containing a regulated quantityof air are supplied to the reactor through inlet nozzle 5. Thereactivating gases are directed by bailie 28 into the annular space 3|,flooding this space and the spaces 32 above the catalyst beds from whichthey flow as a plurality of separate streams downwardly into theindividual catalyst beds and burn the combustible deposits therefrom.The resulting spent or partially spent reactivating gases and combustionproducts pass from the individual catalyst beds through the perforatemembers I9 into spaces 20 from which they flow through openings 2| intothe central conduit. The streams from the several catalyst bedscommingle in the central conduit and are directed therefrom throughsleeve 33 and outlet nozzle 1 to subsequent equipment not pertinent tothe present invention and therefore not illustrated.

The cracking operation is conducted without adding heat to thehydrocarbon vapors following their introduction into the reactor andreactivation is accomplished without abstracting heat from the spentreactivating gases and combustion products in the reactor.

Succeeding the reactivating period, the reactor is substantially purgedof oxygen-containing gases and is then ready to serve as a zone in whichthe cracking reaction may be continued. Thus, two or more reactors ofthe type provided may be connected by means of suitable conduits andstream-diverting valves, not illustrated, to operate alternately asprocessing and reactivating zones so that the cracking reaction may becontinuously conducted with periodic reactivation of the catalyticmaterial in each reactor.

We claim as our invention:

1. A tray for retaining a bed of granular contact material comprising asubstantially cylinthereon extending between said outer wall and saidupwardly extending portion of the central conduit, said perforate meansbeing disposed above and spaced from said closure member, and saidcentral conduit extending slightly above said perforate means and havingopenings provided through its wall at the elevation of the space betweenthe perforate means and the closure member.

2. The tray defined in claim 1, wherein the space between the perforatemeans and the closure member is of increasing height from adjacent saidouter wall to adjacent said central conduit,

3.-The tray defined in claim 1, wherein the space between the perforatemeans and the closure member is of increasing height from adjacent saidouter wall to adjacent said central conduit and wherein upstandingradial stiffening ribs secured to the perforate means and the closuremember are provided within said space.

4. A tray for retaining a bed of granular contact material comprising asubstantially cylindrical outer wall, a closure member connecting thebottom of said outer wall with a depending central conduit substantiallynear the upper end of said depending central conduit, perforate.

means adapted to retain a'bed of granular contact material thereonextending between said outer wall and the said central conduit, saidperforate means being disposed above and spaced from said bottom closuremember, the central conduit having openings provided through its wall atthe elevation of the space between the perforate means and the closuremember, lugs attached to the said outer wall at spaced points around itsbottom periphery for individually supporting said tray, and saiddepending central conduit being of slightly smaller diameter at itslower end so that when two of said trays are fitted together the bottomof said depending cen-" tral conduit of one tray loosely engages withthe upper end of the central conduit just above the perforate means ofthe second said tray.

5. A tray for retaining a bed of granular contact material comprising asubstantially cylindrical outer wall, a closure member connecting thebottom of said outer wall with a depending central conduit substantiallynear the upper end of said depending central conduit, perforate meansadapted to retain a bed of granular contact material thereon extendingbetween said outer wall and the said central conduit, said perforatemeans being disposed above and spaced from said bottom closure member,the the central conduit having openings provided through its wall at theelevation of the space between the perforate means and the closuremember, and said depending central conduit being of slightly smallerdiameter at its lower end so that when two of said trays are fittedtogether the bottom of said depending central conduit of one trayloosely engages with the upper end of the central conduit just above theperforate means of the second said tray.

6. A reactor comprising, in combination, a substantially cylindricalouter shell closed at its opposite ends andprovlded on at least one endwith a removable closure member which spans substantially the fullcross-sectional area of the shell, a plurality of trays of slightlysmaller diameter than said shell, each of said trays com prising asubstantially cylindrical outer wall, a

closure member connecting the bottom of said outer wall with a dependingcentral conduit substantially near the upper end of said dependingcentral conduit, perforate means adapted to retain a bed of granularcontact material thereon extending between said outer wall and the saidcentral conduit, said perforate means being disposed above and spacedfrom said bottom closure member, the central conduit having openingsprovided through its wall at the. elevation of the space between theperforate means and the closure member, said central conduits beingconstructed and arranged so that, when two of the trays are fittedtogether,.the bottom of one of said conduits loosely engages with theupper end ofthe central conduit slightly above the perforate means ofthe second said tray, means for individually supporting the trayson theshell in superimposed spaced apart relationship so that said looselyengaging conduits form a continuous passageway centrally through theshell and with an annular space formed between the outer walls of thetrays and the shell, means for introducing fluid to said annular space,andmeans for removing fluid from said passageway and the shell.

7. The tray defined in claim l, having supporting lugs therefor providedat spaced points about the periphery of its outer wall.

8. The tray defined in claim 1, having a, tubular member, forming a wellfor the reception of a temperature sensitive device, attached to andextending through the outer wall into the space above said perforatemeans wherein said contact material is retained.

9. A tray as defined in claim 1 further characterized in the provisionof a tubu1ar sleeve adapted to slip over the upper end of the centralconduit and extend therefrom to adjacent the top of the'tray, therebyforming an annular space for the reception of said contact materialbetween, said sleeve and said outer wall,

10. In a reactor comprising an outer shell, the combination of aplurality of trays disposed within said shell in superimposedrelationship, perfosaid shell in vertically spaced relation to eachother, perforate catalyst retaining means in each of said trays, .and acentral conduit depending downwardly from each tray and extendingslightly above the perforate means in the tray, said central conduitsbeing constructed and. arranged so that the bottom of a central conduitof an upper tray loosely engages with the end of the central conduitextending slightly above the perforate means of the next lower tray,said central conduits thereby forming a continuous vert'cal passagewaywithin the shell, openings in eac said conduits at an elevation toestablish communication between said passageway and each of the traysbelow the perforate means therein, means for admitting fluid to theshell and the space between the latter and the trays, and

means for removing fluid from said passageway and the shell. 7

LEV A. MEKLER. CLARENCE G. GERHOLD.

